Draft control for tunnel kilns



July 12, 1.932. H. A EVANS v DRAFT CONTROL FOR TUNNEL KILNs 3 Sheets-Sheet l Filed Oct. 28, 1950 *.v,

July 12, 1932. H. A. EVANS DRAFT CONTR'OL- FOR TUNNEL KILNS Filed Oct. 28., 1950 5 SheebS-Sheeb July 12, 1932. H. A. r-:vANs 1,867,066

' DRAFT CONTROL FOR TUNNEL KILNS Filed Oct. 28. 1930 3 Sheets-Sheet 5 Patented July 12, 1932 UNITED STATES DRAFT CONTROL ronf'rrN-L Application sled october 28,"1eso- 'serial N. 491,793. i

In the drawings: Figure 1 is a top plan view of the exit end of my improved kiln.

Figure la is a similar view of the entrance Y 5 end of the kiln.

Figure 2 is a side elevation of the exit end of the kiln. Y c

Figure 2a is a side elevation of the entrance end of the kiln. Y Y

Figure 3 is an enlarged detail view.

Figure 4 is a detail vertical longitudinal section of the kiln. l

Figures 5 and 6 are longitudinal vertical sectional views of a kiln showing, by arrows, the natural and the artificial drafts, respectively, in the kiln.

The primary object of my invention is to provide, in a kiln having a Vheating up zone, one or more high temperature zones, and a cooling zone, through which zones ware travels, means for introducing an air blast 1n the tunnel toward the entrance end of the tunnel or kiln, so that the natural draft, which travels from the entrance end of the kiln through said zones, and toward the eXit end of the kiln, is nullified and the temperature developed in the high temperature zones is prevented from traveling toward the exit end of the kiln; and with this, and other ob- 30 jects in view, my invention consists of the parts, and combination of parts, herein described.

The reference numeral 1 designates a tunnel kiln embodying my invention; the numeral 2 designates the entrance end of the kiln, and the numeral 3 the exit end of the kiln.

Near (preferably) the exit end of the kiln 50 duced from below, or at the sides, or above the I position a blower 4 of suitable capacity to vehicles carrying the ware uneritreatment.' At 4the exit end ofthe tunnel 'la branch pipe 10 leads-trom fthe'sccndut r-and is `.'previcted with nozzle 151 projecting at a higher level than the pipes into the eXit end of the tunnel, $5 the Vpipe 10 being provided with a control valve 12. By means of the valve on Veach ofl the branch p1pes,I can readily control the entrance of the blast'to'the desired or necessary point the tunnel.V 1 1 The high vtemperature zones are p rovided withmufilewalls 13. The stack 15 is nearv the entrance end'of the tunnel.

A blast of air frombelow, or vat the sides -of the vehicle carrying the ware through thel a tunnel, is projected into the tunnel from the branch pipes G'into the currents of air (see arrows 16) induced by the blast from pipe 10 toward the stack near the entrance end of the tunnel. This acts as a counter draft and 'mi damper to the natural draft, indicated by the arrows 14, and accelerates the artificial draft (arrows 16) and causes the heat 'to bank up within a limited area immediately prec ceding the point of entrance of said draft of i air and toward the entrance. i

By my invention I draw the heat radiated Y from the ware and conveyors in the cooling end of the tunnel through the high temperature zone toward the entrance end of the l tunnel so Ythat all heat not lost by radiation Y passes over or vamidst the ware being heated up, in the heating section, thus conserving heat. The amount of draft provided will control the rate at whichV the hot air vwill i j travel toward the entrance end of the tunnel.

What I claim is:

l. In a tunnel kiln having a heating up zone, one or more high temperature zones,1|p and a cooling zone through which the ware travels, an injector arranged at the exit end of the tunnel for introducing a blast of air thereinto for travel toward the 'inlet end of the tunnel, injectors arranged at intervals in the length of the tunnel for injecting blasts of air supplementing the first-named blast, vhereby blasts of air counter to the natural draft of the tunnel are produced to substan- ,A tally nullify such draft, and means for independently controlling the blasts through said injectors. Y

2. In a tunnel having a heatingup zone, one or more high temperature zones, and a 5 cooling zone through Which the Ware travels, a blast device arranged for Y introducing a blast of air into the tunnelat its exitend for traveltoward'fits inlet end,4 a plurality of blast devices arranged at intervals along the 10 lengthV of the tunnel for introducing thereinto blasts 'of air supplementary to the rstnamed r blast of air, said blasts of air operating to Y.

introduce a draf-t current 'in oppositionto Y the natural draft current, .whereby said nat- V15 ural draft current is substantially neutralized, and valves for independently controlling the flow of air through said blast devices. In testimony whereof I afliX my signature.

- HOMER A. EVANS.,;

Jas 

